By John Armstrong

The Labour and Alliance Coalition agreement contains a pioneering "freedom to differ" clause, although it may be used only sparingly to avoid eroding the new Government's unity and credibility.

The safety-valve in the 11/2-page document is designed to get around the strict confines of collective cabinet responsibility.

That long-established convention binds all ministers and prevents them from deviating publicly from a cabinet decision whether or not they agree with it and regardless of their party label.

The agree-to-disagree provision has been inserted into the minimalist document - signed yesterday by Labour leader Helen Clark and her counterpart Jim Anderton - for the protection of the Alliance.

Labour recognises that its minority partner must be allowed to promote different ideas to retain its identity. Otherwise, it will become frustrated and the Coalition will rupture.

The agreement is short on policy detail, being almost exclusively devoted to Coalition management procedures.

Ministers will still have to sign up to cabinet decisions, but in "infrequent" cases, they will be able to promote more radical positions than the cabinet consensus.

The most obvious example is paid parental leave, where the Alliance will want to go further than Labour.

The transparency is also designed to make inevitable tensions over policy appear less out of the ordinary, instead of them being constantly highlighted as Coalition-splitters by Opposition parties and the media.

However, the Prime Minister-designate, Helen Clark, indicated the provision would not be used to resolve arguments over key elements of Coalition policy.

"If it is at the core of the Government's programme, there won't be a split," she said during the signing ceremony in Parliament's old Legislative Council chamber.

She did not expand on that comment. However, public friction over core policies would immediately raise questions about the Coalition's stability.

She later appeared to widen the latitude for disagreement by saying that the Alliance could push its policy of raising tariffs via a private member's bill in Parliament. Such a measure would be defeated by Labour's and other parties' votes, but tariffs are central to economic policy.

The Coalition document allows a partner to advocate separate policy positions and vote in Parliament accordingly, as long as this has been sanctioned by a six-strong Coalition management committee.

Mr Anderton acknowledged the onus was on his party to use the provision responsibly.

"Labour has given the Alliance a lot of rope. The question is whether we choose to hang ourselves or not."

Under the agreement, each leader will be able to raise a "distinctive policy matter" as a matter of party identity.

If unresolved, the management committee, comprising the leaders, their deputies and senior whips, can then identify the issue as involving "party distinction."

Adopting separate positions in speeches or parliamentary votes will then not be a breach of cabinet convention.

However, neither party will be able to divorce itself from a cabinet decision even if it retains a different view.

Neither will the new approach provide carte blanche for an individual minister to buck decisions.

Discretion to sack an Alliance minister remains with the Prime Minister, but Helen Clark would do so only after consulting Mr Anderton.

Helen Clark said the Coalition agreement avoided the detail of the 65-page National and New Zealand First version because both Labour and the Alliance felt this would entail compromise that left neither happy.

Instead, the document confines itself to a broad policy platform of reducing inequality, being environmentally sustainable and improving the social and economic wellbeing of all New Zealanders.